It is generally known that overhead transport systems able to move forward garments hung on hangers have been used for some time; accordingly, these systems basically have the capacity of handling and drawing the hooks of the above-mentioned hangers.
However, these systems are not only used to make the garments move forward one by one; they also more and more often perform the function of sorting these garments in a predetermined order, thanks to their capacity of automatically creating selective garment lots and automatically unloading the subsequent lots that have just been created.
More particularly, the creation of the said lots is made possible by systems equipped with a rotating threaded rail, in a horizontal position, on which appropriate switch devices gradually unload the garments (hung on their hangers) for the purpose of forming every separate lot.
In this case, the hanger hooks that are supported by the said threaded rail are moved forward, precisely thanks to the rotatory motion of the rail, towards the unloading station; in this context, it is obvious that theoretically, every single hanger supported by the rail should rapidly be conveyed towards the unloading station.
Yet considering the fact that the purpose of such a system is to create garment lots (and only afterwards to perform the contemporaneous unloading of each lot), it is easy to understand why the said threaded rail is supplied with a lever which, as long as the garments are accumulating in order to form a lot, is in such a position as to interfere with the hanger hooks, obstructing their forward movement towards the unloading station.
More particularly, this lever which, when in its operational position, is placed very near the said rotating rail, has the function of intercepting the lot's first garment's hanger hook; this first hanger is therefore not only unable to move forwards (although the threaded rail is still rotating), but it naturally also holds up all the hangers of the same lot's subsequent garments that, drawn forward by the rail itself, end up by accumulating tightly behind the first hanger.
Logically, as soon as the required lot formation is complete, the above-mentioned stop lever is removed, so that the whole lot can rapidly be conveyed to the unloading station.
In this connection, it is important to note that the necessity of using the said hook stop lever is linked to the fact that the threaded rail rotation can never be stopped, as it permanently performs a twofold function: on one hand it brings together the separate garments that will then be part of the same lot, and on the other hand it unloads a lot that has been created, while another lot is simultaneously being created behind the stop lever.
In other versions of these traditional transport and sorting systems, the feature that enables the hangers to move forward and therefore the lots to be formed, in collaboration with the same stop lever, consists of a closed circuit chain which is in any case capable of making the hanger hooks which it supports continuously move forward.
However, in both the versions described above, these traditional systems are disadvantaged by some considerable drawbacks with negative effects that appear precisely when the subsequent lots are being formed, in other words when the said hanger hook stop lever is in operational position.
Indeed, the gradually increasing number of hangers that accumulate behind the said stop lever—as a consequence of the drawing action due to the threaded rail or, alternatively, to the closed circuit chain—provokes an increasing resistance which is detrimental to the rotation of the threaded rail itself or to the forward closed circuit motion of the chain itself.
All this means a particularly important stress is put on the devices that are in charge of the rail rotation or the chain forward motion which, in order to take this stress without any risk, must possibly be of a much bigger size than necessary.
Furthermore, this considerable stress put on the said systems naturally also requires a significant consumption of energy, particularly around those “peak” times that occur when the resistance to the forward motion of the systems themselves turns out to be greater because of the substantial number of hangers tightly accumulated one against the other.